Catalytic asymmetric hydrogenation of β-ketoesters using new BINAP complexes of ruthenium

Two new, air-stable BINAP complexes of ruthenium(II), (RCp)Ru(S-(−)-BINAP)Cl (R=1cr; H, CH3) have been prepared in good yield from the reaction of (RCp)Ru(PPh3)2Cl with S-(−)-BINAP in refluxing toluene. The structure of the methylcyclopentadienyl analog has been determined by X-ray crystallography. Both complexes have been found to be effective homogeneous catalysts for the enantioselective hydrogenation of β-ketoesters.